1. Field of the Invention
The invention relates to an image input device having a mechanism for enabling a photographing range to be moved and a mechanism for controlling an image state of the photographed image.
2. Related Background Art
In recent years, a video camera is widely used as an image input device for a computer.
Particularly, as a system in which a video camera and a computer or the like (for example, personal computer or work station) are combined, an electronic mail of an image or a television (TV) conference system is being used.
Hitherto, as a video camera apparatus of the image input device which is used in such an application field, a video camera which has been developed for the application for monitoring, a video camera having a lens which can be controlled by a remote operation, and the like have been known.
In case of using such an image input device for a television conference, however, there are the following various kinds of problems to be solved.
In the image input device as mentioned above, since an angle of camera cannot be remotely controlled, in case of using the image input device in a TV conference or the like, in order to change a photographing range, a plurality of video camera must be prepared and switched, so that its use efficiency is bad.
The video camera has an auto white balance function and an auto focusing function, or the like in which a state of the photographed image is automatically adjusted.
The auto focusing function is a function to automatically adjust a focal point to an in-focus state.
The auto white balance function will now be described.
Even in case of the same object, under different light sources, the spectral characteristics of the light which is reflected from the object are changed by being influenced by the spectral characteristics (light source color) of the light source, so that the color tone of the image plane differs. In this case, however, according to the human feeling, the man feels such that a special color, for example, white on the image plane is sensed as a color different from white which the man himself has stored or felt, so that there is a case where he feels unpleasant. The video camera, accordingly, has an auto white balance (AWB) function adjusting the color tone in accordance with the light source, thereby automatically adjusting the color tone so that the white color can be always seen as white at a predetermined level even under the light source.
As a method of white balance (WB) adjusting methods, there has conventionally been known a method whereby with reference to color difference signals R-Y and B-Y which are obtained by processing a plurality of chrominance signals obtained by, for example, a CCD or the like as an image pickup element, chrominance signals of, for example, three colors of R, G, and B, a control operation to change ratios among the chrominance signals R, G, and B in a manner such that the values obtained by integrating the color difference signals for a certain period of time become mininum is executed, thereby adjusting the WB.
In the video camera having such a WB adjusting function, there is a video camera such that just after the power source was turned on, the WB adjusting operation is automatically executed, thereby enabling a good image of a well-balanced WB to be obtained just after the turn-on of the power source.
However, when the WB adjusting operation of the camera is executed during the pan operation or tilt operation for changing the photographing range, the color of the image which is obtained from the CCD is unstable and the image becomes hard to see.
In case of the TV conference system since information is digitally transmitted, when an amount of information of the image data which is transmitted increases, it takes a time to transmit the information. A time difference occurs between the transmission side and the reception side. Such a drawback becomes a serious problem in a TV conference system which needs to execute operations in a real-time manner.
The invention is made under such circumstances and it is an object of the invention to solve the above problems and to provide an image input device which is particularly effective when the apparatus is used in a TV conference system.
To accomplish the above object, according to one preferred embodiment of the invention, there is provided an image input device comprising: image pickup means for photographing an object image; signal processing means for executing a predetermined signal process to an image signal that is generated from the image pickup means; an optical axis control means for changing an optical axis of a field of view which is photographed by the image pickup means; and control means for interlockingly controlling the image pickup means and the optical axis control means.
The above and other objects, features, and advantages of the invention will become apparent from the following detailed description taken in conjunction with the appended claims with reference to the accompanying drawings.